149 research outputs found
Intertwined effects of climate and land use change on environmental dynamics and carbon accumulation in a mangrove‐fringed coastal lagoon in Java, Indonesia
No full textThe identification and quantification of natural carbon (C) sinks is critical to global climate change mitigation efforts. Tropical coastal wetlands are considered important in this context, yet knowledge of their dynamics and quantitative data are still scarce. In order to quantify the C accumulation rate and understand how it is influenced by land use and climate change, a palaeoecological study was conducted in the mangrove‐fringed Segara Anakan Lagoon (SAL) in Java, Indonesia. A sediment core was age‐dated and analyzed for its pollen and spore, elemental and biogeochemical compositions. The results indicate that environmental dynamics in the SAL and its C accumulation over the past 400 years were controlled mainly by climate oscillations and anthropogenic activities. The interaction of these two factors changed the lagoon's sediment supply and salinity, which consequently altered the organic matter composition and deposition in the lagoon. Four phases with varying climates were identified. While autochthonous mangrove C was a significant contributor to carbon accumulation in SAL sediments throughout all four phases, varying admixtures of terrestrial C from the hinterland also contributed, with natural mixed forest C predominating in the early phases and agriculture soil C predominating in the later phases. In this context, climate‐related precipitation changes are an overarching control, as surface water transport through rivers serves as the “delivery agent” for the outcomes of the anthropogenic impact in the catchment area into the lagoon. Amongst mangrove‐dominated ecosystems globally, the SAL is one of the most effective C sinks due to high mangrove carbon input in combination with a high allochthonous carbon input from anthropogenically enhanced sediment from the hinterland and increased preservation. Given the substantial C sequestration capacity of the SAL and other mangrove‐fringed coastal lagoons, conservation and restoration of these ecosystems is vitally important for climate change mitigation
The future of the past: Applications of paleoecological findings in peatland restoration in Indonesia
No full textEleven month high resolution pollen and spore sedimentation record off SW Java in the Indian Ocean
No full textSettling particles collected in a sediment trap 60 km off SW Java in the Indian Ocean at a 2200 m deep site, about 830 m above the sea floor, between December 2001 and November 2002 (intervals of 16 days for 11 months) were analyzed for the abundance and taxa composition of pollen and spores. Several factors control their deposition such as the monsoon-driven reversal of the wind directions and ocean currents as well as flowering periods. Long distance transport plays a particular role during the monsoon seasons. During the NW monsoon (mid-December-beginning of March), maxima of Picea type, Alnus, Pinus and Quercus pollen occur in the trap samples, which correspond to wind and marine currents coming from the north, probably the Equatorial Counter Current and Southern Java Current, transporting pollen from the southern part of continental Asia and Sumatra to the research area. During the SE monsoon (end of July-mid-November), an increase of pollen originating from southeast Indonesia and Australia was observed. Pollen grains were probably transported by the South Equatorial Current and partly by the Leeuwin Current. Casuarina and, in part, Eucalyptus are most abundant during this period. During the intermonsoon period, assemblages are mainly composed of pollen originating from West Java. Maxima of some pollen taxa, such as Elaeocarpus, Myrica, Dacryccupus type, Casuarina, Eucalyptus and Podocarpus type probably reflect their flowering periods. The transportation time from the pollen source area to the sediment trap is about 1-2 months. The extrapolated pollen accumulation rate of the marine sediment trap would be about 1670 grains/cm(2)/yr. The trap collected low concentrations of mangrove pollen, which might be the result of the strong destruction of the mangrove belt in Java during recent decades. High values of Poaceae pollen are probably related to the land use, forest canopy opening and development of the secondary vegetation in West Java. The majority of the pollen and spores collected by the sediment trap reflects the vegetation of SW Java, but long distance transport, in particular by the marine currents during the SE and NE monsoons, needs to be considered when interpreting marine pollen records off SW Java in the eastern Indian Ocean. (C) 2014 Elsevier B.V. All rights reserved
Two-step vegetation response to enhanced precipitation in Northeast Brazil during Heinrich event 1
No full textHigh resolution palynological and geochemical data of sediment core GeoB 3910-2 (located offshore Northeast Brazil) spanning the period between 19 600 and 14 500 calibrated year bp (19.6-14.5 ka) show a land-cover change in the catchment area of local rivers in two steps related to changes in precipitation associated with Heinrich Event 1 (H1 stadial). At the end of the last glacial maximum, the landscape in semi-arid Northeast Brazil was dominated by a very dry type of caatinga vegetation, mainly composed of grasslands with some herbs and shrubs. After 18 ka, considerably more humid conditions are suggested by changes in the vegetation and by C(org) and C/N data indicative of fluvial erosion. The caatinga became wetter and along lakes and rivers, sedges and gallery forest expanded. The most humid period was recorded between 16.5 and 15 ka, when humid gallery (and floodplain) forest and even small patches of mountainous Atlantic rain forest occurred together with dry forest, the latter being considered as a rather lush type of caatinga vegetation. During this humid phase erosion decreased as less lithogenic material and more organic terrestrial material were deposited on the continental slope of northern Brazil. After 15 ka arid conditions returned. During the humid second phase of the H1 stadial, a rich variety of landscapes existed in Northeast Brazil and during the drier periods small pockets of forest could probably survive in favorable spots, which would have increased the resilience of the forest to climate change
Asynchronous terrestrial and marine signals of climate change during Heinrich events
No full textTropical regions have been reported to play a key role in climate dynamics. To date, however, there are uncertainties in the timing and the amplitude of the response of tropical ecosystems to millennial-scale climate change. We present evidence of an asynchrony between terrestrial and marine signals of climate change during Heinrich events preserved in marine sediment cores from the Brazilian continental margin. The inferred time lag of about 1000 to 2000 years is much larger than the ecological response to recent climate change and appears to be related to the nature of hydrological changes. The recent increase in extreme climatic events, particularly in tropical regions, is thought by many to be a precursor of climate change. High-resolution investigations of past climate oscillations have found that changes between climate modes (warm versus cold and dry versus wet) can occur within decade
Resilience of a peatland in Central Sumatra, Indonesia to past anthropogenic disturbance: Improving conservation and restoration designs using palaeoecology
No full textCalcium carbonate flux and particulate silica flux of sediment trap NBBT-S, northern Bay of Bengal trap
No full textCalcium carbonate flux and particulate silica flux of sediment trap NBBT-S, northern Bay of Bengal tra
Late Holocene ENSO-related fire impact on vegetation, nutrient status and carbon accumulation of peatlands in Jambi, Sumatra, Indonesia
No full textEnvironmental dynamics and carbon accumulation rate of a tropical peatland in Central Sumatra, Indonesia
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